CE 428 Water and Wastewater Treatment Design
Problem Set 1
Due Date: Feb. 4
1.
Complete the Table
Chemical ConcenSpecies
tration
(mg/L)
Na+
23
Ca2+
40
NO362
PO4395
CaCO3
100
H2SO4
49
CO2
22
Molecular
Weight
Valency
Equivalent
Weight
moles/
liter
Milliequivalent/
liter
mg/L as
CaCO3
Based on the above, comment on any relationships for the conversion of concentrations from one unit to
another. (Note that CO2 reacts with water to form H2CO3, use H2CO3 to figure out the valency of CO2)
2.
500 mg of Ca(HCO3)2 is dissolved in 750 mL of distilled water. What is the:
(a) molar concentration (moles/L)
(b) concentration in milliequivalent/L
(c) concentration in mg/L
(d) concentration in mg/L as CaCO3
(e) concentration in mg/L as C
3.
Determine the total solids, suspended solids, total volatile solids, dissolved solids for a water sample. The
following experiments were conducted:
(i)
(a) Volume of water sample = 100 mL. Weight of evaporation dish = 68.942 gm.
100 mL of the sample was poured on the evaporating dish and the water was evaporated.
Weight of dish plus residues = 69.049 gm.
(b) The dish was then placed in a muffle furnace and heated at 550 o C. The weight of the
dish and residue remaining was 68.980 gm.
(ii)
Weight of 1 micron filter paper and dish = 1.456 gm. 500 mL of the water sample was
filtered through the 1 micron filter paper. The paper and dish was dried at 105 o C for 24
hours. The final weight of the dish and filter paper = 1.522 gm.
4.
Provide a one page summary on Boston sewer system, compliance with the Clean Water Act and the Deer
Island wastewater treatment plant. Example websites are:
http://cwx.prenhall.com/bookbind/pubbooks/nebel2/medialib/update17.html
http://www.mwra.state.ma.us/03sewer/html/sew.htm
See:
The History of the Sewer System
Deer Island Sewage Treatment Plant
5.
An inline equalization basin is to be designed for a wastewater treatment plant. The plant records are as
shown below. Determine the volume required for the basin.
Time
12 am
1
2
3.
4
5
6
7
8
9
10
11
12 noon
Flowrate (gpm)
1740
1630
1390
1180
1040
910
910
920
1530
2080
2270
2330
2330
Time
1 pm
2
3
4
5
6
7
8
9
10
11
12
Flowrate
2330
2290
2220
2220
2150
2010
1940
1940
1880
1630
1560
1740